Challenging Job May Protect Damaged Brain

Effects of vascular pathology possibly mitigated by complex work

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Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.

In subjects with normal cognition but at risk for Alzheimer's (AD), those with higher occupational complexity are better able to withstand pathology associated with AD and cerebrovascular disease and perform at a similar cognitive level as their peers with less brain pathology.

Note that those who worked predominantly with other people, rather than with data or with physical things, garnered the most protective effects on so-called cognitive reserve.

TORONTO -- Having a more complex job may offset the effects of vascular damage in the brain and potentially protect against Alzheimer's disease, researchers reported here.

In an analysis of data from patients with normal cognition in the Wisconsin Registry for Alzheimer's Prevention (WRAP), those with more white matter hyperintensities on brain scans also tended to be those with mentally challenging occupations, Ozioma Okonkwo, PhD, of the University of Wisconsin, and colleagues reported at the Alzheimer's Association International Conference here.

Those who worked predominantly with other people -- rather than with data or with physical things -- garnered the most protective effects, the researchers said, suggesting that social interaction plays a unique role in cognitive reserve.

"People with more complex jobs are able to tolerate more white matter hyperintensities and still have better cognition than those who had less challenging jobs," Maria Carrillo, PhD, chief medical officer of the Alzheimer's Association, who wasn't involved in the study, told MedPage Today. "It's a surrogate for cognitive reserve."

The idea of cognitive reserve has gained widespread acceptance in the Alzheimer's field. It refers to the retention of cognitive function despite having pathology in the brain normally associated with dementia.

Cognitive reserve is typically associated with greater educational attainment or complex work environments -- raising the question of whether modifiable factors could offer protection against Alzheimer's disease and other forms of dementia.

For their study, Okonkwo and colleagues assessed 284 healthy patients from WRAP, mean age 60, who were at risk for Alzheimer's disease. About two-thirds were female, 71% had a family history of Alzheimer's disease, 37% were APOE e4 positive, and the mean educational attainment was a 4-year college degree.

All patients had a work history assessment to determine their composite score for occupational complexity; they were also grouped by three types of jobs: working with people, with data, or with physical things. Working with people included mentoring, working with data included comparing or synthesizing information, and working with things included handling items.

Patients also had T2FLAIR structural MRI to determine white matter hyperintensities, which are indicative of cerebrovascular disease, and their cognition was assessed using four parameters: verbal learning and memory, speed and flexibility, working memory, and immediate memory.

Those with higher occupational complexity appear to be better able to withstand the pathology associated with Alzheimer's disease and cerebrovascular disease and perform at a similar cognitive level as their peers, the researchers said.

In further analyses, however, Okonkwo and colleagues saw that this relationship was only significant for those working with people, not with data or things (t=2.04, P=0.04).

The findings "underscore the importance of social engagement in the work setting for building resilience to Alzheimer's disease," they said.

They concluded that their data support the cognitive reserve hypothesis, but they acknowledged a need for further study.

Carillo said the growth of cognitive reserve studies "shows the maturity of our field in that it's broadening beyond therapeutics."

She noted that many experts have "their own take on what cognitive reserve actually is, but in general, the more you challenge your brain, the more complex connections can be made. The more enriched networks you have, the more you can tolerate assaults on your brain."

Gary Small, MD, of the University of California Los Angeles, who wasn't involved in the study, agreed that cognitive reserve "is a fuzzy concept," but said it essentially means that "someone with denser neuronal networks won't see the same ravages of the disease."

Even though the science behind cognitive reserve is still evolving, Small said there is a lot of evidence that healthy behaviors such as diet and exercise are associated with better cardiovascular and brain health.

"It makes sense to do things that keep the mind active and engaged," he told MedPage Today. "We don't have any head-to-head comparisons on which strategies are the most effective. But I recommend that people engage in the mental activities that they enjoy."

John Morris, MD, of Washington University in St. Louis, agreed that most dementia experts are already encouraging their patients to remain physically, mentally, and socially active.

But he warned that the caveat that association doesn't prove causality remains.

"People who play bridge may be less likely to develop Alzheimer's disease, but it may have nothing to do with playing bridge," he told MedPage Today. "Perhaps bridge players were born with a bigger or better brain, or raised in an environment that encouraged healthy living, or other factors that protect them against illnesses such as Alzheimer's disease."

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